What is theWhat is the Ozone Hole?! Ozone Hole?!What is theWhat is the Ozone Hole?! Ozone Hole?!

By HayanonTranslated by Y. Noda and Y. KamideSupervised by K. Takahashi

When a beam of sunlight passes through a prism, the rays of different wavelengths come out.

The ozone layer lies about 15 - 40 km in altitude, although this height varies with latitude. <Courtesy of WMO Report “Scientific Assessment of Ozone Depletion 2002”>

Alti

tude

(kilo

met

ers)

Ozone concentration

Ozone Layer

Ozoneincreases

from pollution

StratosphericOzone

TroposphericOzone

O3

About 90% of the Earth‛s ozone is found in the stratosphere. Let‛s see briefly the history of stratospheric ozone: Who discovered it, and how?

Sunlight is made up of different electromagnetic waves, ranging from short wavelength ultraviolet to long wavelength infrared. Do you think this is a difficult subject? Imagine a rainbow or a prism. You see different colors in a rainbow, and that indicates that sunlight contains various light waves.

In 1881, an Irish chemist W. N. Hartley found that ozone absorbs ultraviolet at wavelengths from 200 to 300 nanometers . Fifteen years later W. Huggins, an English astronomer, studied the spectra of the dog star Sirius and discovered ozone absorption of ultraviolet at wavelengths from 300 to 340 nanometers.

A nanometer is one billionth of a meter.

Hartley asked why ultraviolet rays are not detected in sunlight at the Earth‛s surface, although they exist just after being radiated from the Sun. He suggested that there was a large quantity of ozone up in the sky that absorbs ultraviolet radiation. An experiment with a balloon was carried out to confirm his idea, but the balloon did not get as high as the ozone layer.

Finally in the 1940s, rocket observations showed the existence of stratospheric ozone. Unfortunately, Hartley had already passed away by then. Various research projects started following the finding to understand the ozone distribution, its birthplace, etc. Ozone observations began in Antarctica in 1957 as part of the International Geophysical Year. At that time, no one could predict that these observations would lead to the discovery of the ozone hole.

As research has progressed, people began to acknowledge that animal and plant life is protected by the ozone layer that absorbs harmful ultraviolet. Behind today‛s research lie the accomplishments of scientists like Hartley, who first studied the chemical, ozone.

We hope you readers share an adventure trip into ozone with our Mol and Mirubo!

1

Mirubo,what do youthink there isabove theclouds? Above the

clouds?Hmm...

The skyshould beup there.

glancing at drifting clouds, lying on their backs in the meadowon a nice and warm day.

Here are science lover Mol and her robotic dog Mirubo ...

2

Don't youhave theslightest imagination?

I expect youto tell mesomethinginteresting.

She is at arebelliousage.

Of course I haveimagination.It would be nice ifthere was a hugefood court overthe clouds.

Wait!I remember ... high above the

clouds isthe ozone layer.

I heardthatbefore.

What isthat?

The ozonelayer?

Boo- boo

3

Sensei, wouldyou explainto us whatozone is?

Sure!It's myfield.

Now,Mol andMirubo, ...

how much doyou know aboutozone?

Uhmm......??

How aboutoxygen,then?

Oh, I knowa lot.

I take ina vast amountof oxygeneveryday.

Ozoneexists highabove us ...

It consists of oxygenatoms.

Breeeathe!

Wow!!

When an oxygenmolecule (O2)is struck byultraviolet rays, ...

it splitsinto twooxygenatoms.

Then, a singleoxygen atomcombines withanother oxygenmolecule.

Three oxygenatoms finallyform an ozonemolecule (O3).

The area whereozone moleculesconcentrate iscalled ... the

ozone layer!

The ozone layerabsorbs much ofthe ultravioletradiation which isharmful to life.

Just like ashield, theozone layerprotects theEarth.

Withoutthe ozonelayer, ...

there would beno life on theEarth.

4

Waaahhh!Ultravioletradiation isdangerous!

Calm down.We have theozone layerprotecting us.

No need toworry.

Let me remindyou that thereis a worry.

Whaaaat?!

In the 1980s,scientists foundthat ozone wasbeing lost overAntarctica. It looks like

there is a

holein the ozonelayer.

More ultravioletradiation iscoming throughthe hole??

Antarctica

That isa crisis!!

Wait.

The ozone holeexists over Antarctica, notJapan.

We are safe,anyway.

No!! Penguinswill getsunburned!

Don‛t tellme you areserious.

5

Hip, hip,hurray!

What aWhat arelief!relief!

We can‛t saywe are safe fromthe ozone holeover Antarctica.

Its influencereaches usno matterhow far it is.

In fact, a similarphenomenon isobserved overthe Arctic.

It is an importantissue for thepeople living inthe area.

Whatpunches theholes in theozone layer??

CFCs, stands forchlorofluoro-carbons, thesemake the holes.

Until some tenyears ago, CFCs werewidely used for ... air conditioners,

refrigerators,spray cans, etc.

And how??

6

Now we know that CFCsemitted by human activitiestravel with the air flow andascend to the stratosphere. In the stratosphere

they are destroyingthe ozone layer!

When this researchresult was released,it showed the needto set regulationsfor the use of CFCs.

However, weneed airconditioners,refrigerators,etc.

Substitutesfor CFCs

I doubt thatthe ozone losswill be stoppedsoon afterpeople abandonCFCs.

Exactly.

CFCs are highlystable compoundsand require a longtime to decompose.

then began to beused for thoseappliances.

7

Noop! When willthe ozone hole bestitched?

Recent research using a supercomputer shows that theozone hole will closein 50 years.

50 years?!Does it takeso long?!

Yes, and untilthat time, theozone hole willcontinue toexist.

That istoo bad.

All we can dois wait for therecovery of theozone layer?!

Or, will it neverbe filled in?

8

Are there anyways to fixthe hole?

Yes!

I just got a bright idea!

How aboutdispersing ozoneinto the sky! It will

surely work!

I am sorryto say thatis impossible.

Oh, why not?

Of course theozone layer in thestratosphere is protecting us.

However, ozoneitself is deadly

poisonousfor all life.

About 90% of theozone in the Earth‛s atmosphere is in the stratosphere and 10% in the troposphere.

The ozone in thetroposphere, whichis closer to us, is actually increasing!!

90%

10%

Mm-hm ...

What!!

Hammering

or stitching?

O3

9

The concern overits impact on life isgrowing. Besides, it isthought to be a factor

in global warmingglobal warming.In the troposphere themore ozone increases,the more energy,normally released fromthe Earth into space, is absorbed.

Ozone is abaddie?!

Ozone has aJekyll-and-Hyde nature.

Ozonedepletion in theupper part is aproblem.

At the same time,its increase in thelower part is alsoa problem.

Isn‛t it strange?

Bothproblemsare critical.

CFC regulationshave been set totackle ozonedepletion in thestratosphere.

On the otherhand, nitrogendioxide emissionsfrom vehicles andindustries are ...

Umm ...

controlled toreduce nitrogenoxides, which generate ozone inthe troposphere.

10

Wha

Wha amam

Studies are beingcarried out aboutstratospheric andtropospheric ozone.

It would be nice if100 years from nowpeople say, “There wasan ozone hole along time ago ...”

Yeah,I hope thatwill happen.

I never realizedthat the ozonelayer above theclouds keepsthe Earth safe.

That isimpressive!

Now, we have toprotect the ozonelayer in return. Yes, let‛s

think whatwe can doabout that.

Thus,countermeasures can be taken to prevent their condition from deteriorating.

11

HaHaHaHaHaHa

What is the Ozone Hole?!Hello, Sensei! I recently read a news article about the ozone hole. Is it true that the ozone layer protects humans, animals, and plants?

Yes. The ozone layer covers the Earth and acts as a shield against ultraviolet radiation from the Sun. It is like an invisible but well-built shell.

Ultraviolet means nothing to a super high tech robot like me.

All right. How old do you think the ozone layer is?

Let me see ... I guess it had been formed long before the first human was born.

The Earth is about 4.6 billion years old. The ozone layer is believed to have been created about 400 million years ago.

Ozone had already existed before the age of dinosaurs, from 250 million to 65 million years ago. The ozone layer formed slowly over billions of years!

That‛s right! Thanks to the ozone layer, life on Earth was made possible. Without it, there would be no life. Mirubo, you are not the exception.

What will happen if ozone in the ozone layer decreases?

Well, more ultraviolet radiation would come to the Earth and may cause severe damage to life.

Ultraviolet radiation can cause sunburn. You will be charred, Mol.

Nooo!

It will be even worse. Ultraviolet radiation destroys DNA and increases the risk of skin cancer. It has also been shown that proteins in the eye‛s lens can be damaged by being exposed to excessive ultraviolet light, which will result in cataracts. A cataract causes cloudy or blurry vision.

Oh, I am very worried about the ozone layer. How is it surveyed? It lies so high above us.

Do you have an alien colleague to ask to observe the ozone layer from a UFO?

Not exactly, but something like it.

Really?? I was just kidding ...

We have satellites for observing the ozone layer from space. They are encircling the Earth and measuring ozone over Japan, Europe, Antarctica, etc.

Are there any other ways?

Yes. Ground observations give data of the status of ozone even at high altitudes. We use laser radars or other measures of detecting radio waves emitted by ozone. Instrument malfunctions can be corrected much easier on the ground than in space.

I got it! A repair shop should be set up in space for satellites and for myself. If there is, a space trip will become more comfortable for me.

Oh, keep to the point, Mirubo.

Photo 1 Drop orange peels into the flask, and wait 30 seconds.

Photo 2 There is smoke without fire!

Photo 3 Smog in Seattle. A brownish haze hangs around above the horizon.

I hope you have enjoyed the scientific adventure trip of Mol and Mirubo. We are currently facing two ozone problems. One is ozone depletion in the stratosphere causing the ozone hole. The other is an increase in tropospheric ozone, which is a component of photochemical smog. Now, I will show you a magical experiment for understanding more about ozone.

What I need is an orange I bought at a nearby supermarket and a glass flask like those you find in a laboratory of your school. Both are nothing special. First, peel the orange and drop a few pieces of the rind into a flask. Photo 1 was taken just after doing this. Do you say “nothing changes”? Be patient! About 30 seconds later, white smoke appears (see Photo 2)!! What happens in the flask, and what makes the white smoke?

Before answering these questions, I will explain about photochemical smog. Have you seen distant mountains covered by whitish or brownish haze that stops you taking scenic photos for souvenirs? This haze, which happens more frequently in some big cities in the world, is closely related to smog (see Photo 3). Smog changes its color and thickness hour to hour, and its frequency varies by the time of day and even year. Such weather conditions as sunlight intensity, wind direction, etc. affect the occurrence of smog.

Smog is made of hydrocarbons and nitrogen dioxide emitted by industries or vehicles, and ozone. A complex set of chemical reactions involving hydrocarbons and ozone forms smog. Small particles are found in smog, and they scatter light. That is why the visibility of distant objects decreases. Smog can irritate your eyes and throat. It is also said to be harmful to all living things, for example, scorching leaves.

Now, let‛s get back to the point. There are no gimmicks or tricks in the magical experiment. Actually, I put a small amount of ozone into the flask in advance. Ozone is a colorless gas and cannot be seen as Photo 1 shows. Orange peel gives a chemical of the hydrocarbon family, limonene, which is a source of the invigorating

scent we smell when we eat an orange. The chemical reaction between ozone and limonene created the smoke in the flask. This is a model of how smog is formed!

On the ground, hydrocarbons are emitted by industries and vehicles, and produce photochemical smog by reacting with ozone. Scientists around the world are working to understand its detailed mechanism.

WARNING: THIS EXPERIMENT IS POTENTIALLY DANGEROUS. DO NOT TRY TO PRACTICE IT WITHOUT PROPER SUPERVISION!

Produced by the Solar-Terrestrial Environment Laboratory, Nagoya University and the Scientific Committee on Solar-Terrestrial Physics in conjunction with the CAWSES program.October 2005 All rights reserved.

Climate and Weather of the Sun-Earth System (CAWSES)

CAWSES is an international program sponsored by SCOSTEP (Scientific Committee on Solar-Terrestrial Physics) and has been established with the aim of significantly enhancing our understanding of the space environment and its impacts on life and society. The main functions of CAWSES are to help coordinate international activities in observations, modeling and theory crucial to achieving this understanding, to involve scientists in both developed and developing countries, and to provide educational opportunities for students at all levels. The CAWSES office is located at Boston University, Boston, MA, USA. The four science Themes of CAWSES are shown in the figure.http://www.bu.edu/cawses/http://www.ngdc.noaa.gov/stp/SCOSTEP/scostep.html

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“What is the Ozone Hole ?!” is published with cooperation of “Kodomo no Kagaku.”Mol, Mirubo, and Sensei thank Joe Allen and David Kerridge for their help in preparing the English version of our story.

Kodomo no Kagaku (Science for Children)

Kodomo no Kagaku, published by the Seibundo Shinkosha Publishing Co., Ltd. is a monthly magazine for juniors. Since the inaugural issue in 1924, the magazine has continuously promoted science education by providing various facets of science, from scientific phenomena in everyday life to cutting edge research topics.http://www.seibundo.net/

HayanonGraduated from the Department of Physics of Ryukyu University, Hayanon, a writer and cartoonist, has contributed a number of serials in popular magazines on the basis of her strong background in science and computer games. Her consistent writing style, expressing a love for science, is well accepted.http://www.hayanon.jp/

Solar-Terrestrial Environment Laboratory (STEL), Nagoya University

STEL is operated under an inter-university cooperative system in Japan. Its purpose is to promote "research on the structure and dynamics of the solar-terrestrial system," in collaboration with a number of universities and institutions both in Japan and abroad. The Laboratory consists of four research Divisions: Atmospheric Environment, Ionospheric and Magnetospheric Environment, Heliospheric Environment, and Integrated Studies. The Geospace Research Center is also affiliated to the Laboratory to coordinate and promote joint research projects. At its seven Observatories/Stations, ground-based observations of various physical and chemical entities are conducted nationwide.http://www.stelab.nagoya-u.ac.jp/